﻿using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;


public class BitmapRegion
{
    public BitmapRegion()
    { }

    /// <summary>
    /// Create and apply the region on the supplied control
    /// </summary>
    /// <param name="control">The Control object to apply the region to</param>
    /// <param name="bitmap">The Bitmap object to create the region from</param>
    public static void CreateControlRegion(Control control, Bitmap bitmap)
    {
        // Return if control and bitmap are null
        if (control == null || bitmap == null)
            return;

        // Set our control's size to be the same as the bitmap
        control.Width = bitmap.Width;
        control.Height = bitmap.Height;

        // Check if we are dealing with Form here
        if (control is System.Windows.Forms.Form)
        {
            // Cast to a Form object
            Form form = (Form)control;

            // Set our form's size to be a little larger that the bitmap just 
            // in case the form's border style is not set to none in the first place
            form.Width += 15;
            form.Height += 35;

            // No border
            form.FormBorderStyle = FormBorderStyle.None;

            // Set bitmap as the background image
            form.BackgroundImage = bitmap;

            // Calculate the graphics path based on the bitmap supplied
            GraphicsPath graphicsPath = CalculateControlGraphicsPath(bitmap);

            // Apply new region
            form.Region = new Region(graphicsPath);
        }

        // Check if we are dealing with Button here
        else if (control is System.Windows.Forms.Button)
        {
            // Cast to a button object
            Button button = (Button)control;

            // Do not show button text
            //button.Text = "";

            
            // Change cursor to hand when over button
            button.Cursor = Cursors.Hand;

            // Set background image of button
            button.BackgroundImage = bitmap;
            button.BackColor = Color.Transparent;

            // Calculate the graphics path based on the bitmap supplied
            GraphicsPath graphicsPath = CalculateControlGraphicsPath(bitmap);

            // Apply new region
            button.Region = new Region(graphicsPath);
        }
        else if (control is PictureBox)
        {
            PictureBox ptBox = (PictureBox)control;
            ptBox.Cursor = Cursors.Hand;
            ptBox.Width = bitmap.Width;
            ptBox.Height = bitmap.Height;
            ptBox.Image = bitmap;
            ptBox.BackColor = Color.Transparent;
        }
    }

    /// <summary>
    /// Calculate the graphics path that representing the figure in the bitmap 
    /// excluding the transparent color which is the top left pixel.
    /// </summary>
    /// <param name="bitmap">The Bitmap object to calculate our graphics path from</param>
    /// <returns>Calculated graphics path</returns>
    public static GraphicsPath CalculateControlGraphicsPath(Bitmap bitmap)
    {
        // Create GraphicsPath for our bitmap calculation
        GraphicsPath graphicsPath = new GraphicsPath();

        // Use the top left pixel as our transparent color
        Color colorTransparent = bitmap.GetPixel(0, 0);

        // This is to store the column value where an opaque pixel is first found.
        // This value will determine where we start scanning for trailing opaque pixels.
        int colOpaquePixel = 0;

        // Go through all rows (Y axis)
        for (int row = 0; row < bitmap.Height; row++)
        {
            // Reset value
            colOpaquePixel = 0;

            // Go through all columns (X axis)
            for (int col = 0; col < bitmap.Width; col++)
            {
                // If this is an opaque pixel, mark it and search for anymore trailing behind
                if (bitmap.GetPixel(col, row) != colorTransparent)
                {
                    // Opaque pixel found, mark current position
                    colOpaquePixel = col;

                    // Create another variable to set the current pixel position
                    int colNext = col;

                    // Starting from current found opaque pixel, search for anymore opaque pixels 
                    // trailing behind, until a transparent pixel is found or minimum width is reached
                    for (colNext = colOpaquePixel; colNext < bitmap.Width; colNext++)
                        if (bitmap.GetPixel(colNext, row) == colorTransparent)
                            break;

                    // Form a rectangle for line of opaque pixels found and add it to our graphics path
                    graphicsPath.AddRectangle(new Rectangle(colOpaquePixel, row, colNext - colOpaquePixel, 1));

                    // No need to scan the line of opaque pixels just found
                    col = colNext;
                }
            }
        }

        // Return calculated graphics path
        return graphicsPath;
    }
}